Acoustic Devices with Directional Reinforcement

Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.

The present disclosure is directed to acoustic devices, such as piezoelectric microelectromechanical systems (MEMS) microphones, and in particular to acoustic devices with directional reinforcement.

A MEMS microphone is a micro-machined electromechanical device used to convert sound pressure (e.g., voice sound) to an electrical signal (e.g., voltage). MEMS microphones are widely used in mobile devices, headsets, smart speakers and other voice-interface devices or systems. Conventional capacitive MEMS microphones suffer from high power consumption (e.g., large bias voltage) and reliability, for example when used in a harsh environment (e.g., when exposed to dust and/or water).

Piezoelectric MEMS microphones have been used to address the deficiencies of capacitive MEMS microphones. Piezoelectric MEMS microphones offer a constant listening capability while consuming almost no power (e.g., no bias voltage is needed), are robust and immune to water and dust contamination. Existing piezoelectric MEMS microphones include cantilever MEMS structures, and are mostly based on sputter-deposited thin film piezoelectric structure. Such thin piezoelectric film suffers from large residual stress and stress gradient across the film thickness after deposition which results in sensitivity degradation and variation. The cantilever MEMS structure suffers from poor low-frequency roll-off control as the gap between cantilevers varies due to cantilever deflection induced by residual stress and stress gradient of the piezoelectric film for a single or multiple films stacked together. Additionally, the cantilever MEMS structure with gap control mechanism can have a complex structure that results in higher manufacturing costs and poor reliability performance.

Accordingly, there is a need for an improved acoustic device with directional reinforcement that can be used, for example, in piezoelectric MEMS microphones and do not suffer the deficiencies in existing MEMS cantilever structures.

In accordance with one aspect of the disclosure, an acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) is provided that includes a substrate and a cantilever beam attached to the substrate. The cantilever beam has a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam, the beam extending in a first direction between the proximal portion and the free end, the distal portion of the beam having a corrugated section including one or more grooves that extend generally in the first direction. Sound pressure exerted on the beam causes the beam, including the corrugated section to bend. The corrugated section inhibits bending along the length of the distal portion when the acoustic sensor is subjected to sound pressure. An electrode is disposed on or in the proximal portion of the beam.

In accordance with another aspect of the disclosure, a piezoelectric sensor for a piezoelectric MEMS microphone is provided. The sensor comprises a substrate and a cantilever beam. The cantilevered beam has a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam. The beam extends in a first direction between the proximal portion and the free end, the distal portion of the beam having a corrugated section including one or more grooves that extend generally in the first direction. An electrode is disposed on or in the proximal portion of the beam.

In accordance with another aspect of the disclosure, a piezoelectric MEMS microphone is provided. The microphone comprises a substrate and a plurality of piezoelectric sensors movably coupled to the substrate. Each of the piezoelectric sensors are spaced apart from an adjacent piezoelectric sensor by a gap. Each piezoelectric sensor includes a cantilever beam having a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam. The beam extends in a first direction between the proximal portion and the free end. The distal portion of the beam has a corrugated section including one or more grooves that extend generally in the first direction, and an electrode disposed on or in the proximal portion of the beam. The plurality of piezoelectric sensors are configured to deflect when subjected to sound pressure.

In accordance with another aspect of the disclosure, an audio subsystem is provided. The audio subsystem comprises an audio codec and one or more piezoelectric MEMS microphones in communication with the audio codec. Each microphone includes a substrate and a plurality of piezoelectric sensors movably coupled to the substrate. Each of the piezoelectric sensors are spaced apart from an adjacent piezoelectric sensor by a gap. Each piezoelectric sensor includes a cantilever beam having a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam. The beam extends in a first direction between the proximal portion and the free end. The distal portion of the beam has a corrugated section including one or more grooves that extend generally in the first direction, and an electrode disposed on or in the proximal portion of the beam.

In accordance with another aspect of the disclosure, an electronic device is provided. The electronic device comprises a processor and an audio subsystem that communicates with the processor. The audio subsystem comprises one or more piezoelectric MEMS microphones on a substrate layer. Each microphone includes a substrate and a plurality of piezoelectric sensors movably coupled to the substrate. Each of the piezoelectric sensors are spaced apart from an adjacent piezoelectric sensor by a gap. Each piezoelectric sensor includes a cantilevered beam having a proximal portion attached to the substrate and a distal portion that extends from the proximal portion to a free end of the beam. The beam extends in a first direction between the proximal portion and the free end. The distal portion of the beam has a corrugated section including one or more grooves that extend generally in the first direction, and an electrode disposed on or in the proximal portion of the beam.

In accordance with another aspect of the disclosure, a method of making an acoustic sensor (e.g., a piezoelectric sensor for a piezoelectric MEMS microphone) is provided. The method comprises forming or providing a mold extending along a length and having one or more grooves in a top surface of the mold, the one or more grooves extending in a direction of the length of the mold to a distal end of the mold. The method also comprises forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the one or more grooves of the mold. The method further comprises releasing the structure from the mold to form a cantilever.

In accordance with another aspect of the disclosure, a method of making an electronic device is provided. The method comprises forming or providing a printed circuit board that includes a substrate layer. The method also comprises forming or providing one or more piezoelectric microelectromechanical systems microphones via a process comprising (a) forming or providing a mold extending along a length and having one or more grooves in a top surface of the mold, the one or more grooves extending in a direction of the length of the mold to a distal end of the mold, (b) forming or depositing a structure having one or more piezoelectric layers over the top surface of the mold to define a beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the one or more grooves of the mold, (c) releasing the structure from the mold, and (d) leaving a part of the structure attached to a substrate in a cantilevered manner to form a cantilever beam that deflects when subjected to sound pressure. The method also comprises mounting the one or more piezoelectric microelectromechanical systems microphones on the printed circuit board.

The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings were like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings.

1 FIG. 300 300 10 10 10 10 10 10 301 10 10 301 302 302 is a schematic diagram of an audio subsystem. The audio subsystemcan include one or more microphones,A. In one implementation, at least one of the microphone(s),A is a piezoelectric MEMS microphone. The microphone(s),A can communicate with an audio codec, which can control the operation of the microphone(s),A. The audio codeccan also communicate with a speakerand control the operation of the speaker.

2 FIG.A 200 300 200 210 220 230 240 250 210 240 200 is a schematic diagram of an electronic devicethat includes the audio subsystem. The electronic devicecan optionally have one or more of a processor, a memory, a user interface, a battery(e.g., direct current (DC) battery) and a power management module. Other additional components, such a display and keyboard can optionally be connected to the processor. The batterycan provide power to the electronic device.

200 210 200 It should be noted that, for simplicity, only certain components of the electronic deviceare illustrated herein. The control signals provided by the processorcontrol the various components within the electronic device.

210 220 210 220 200 2 FIG.A The processorcommunicates with the user interfaceto facilitate processing of various user input and output (I/O), such as voice and data. As shown in, the processorcommunicates with the memoryto facilitate operation of the electronic device.

220 200 The memorycan be used for a wide variety of purposes, such as storing data and/or instructions to facilitate the operation of the electronic deviceand/or to provide storage of user information.

250 200 250 250 The power management system or moduleprovides a number of power management functions of the electronic device. In certain implementations, the power management systemincludes a PA supply control circuit that controls the supply voltages of power amplifiers. For example, the power management systemcan change the supply voltage(s) provided to one or more power amplifiers to improve efficiency.

2 FIG.A 250 240 240 200 As shown in, the power management systemreceives a battery voltage from the battery. The batterycan be any suitable battery for use in the electronic device, including, for example, a lithium-ion battery.

2 FIG.B 2 FIG.A 2 FIG.A 2 FIG.A 2 FIG.B 200 200 200 200 200 200 200 is a schematic diagram of a wireless electronic device′ The wireless electronic device′ is similar to the electronic devicein. Thus, reference numerals used to designate the various components of the wireless electronic device′ are identical to those used for identifying the corresponding components of the electronic devicein. Therefore, the structure and description above for the various features of the electronic deviceinare understood to also apply to the corresponding features of the wireless electronic device′ in, except as described below.

200 200 260 210 260 210 260 260 The wireless electronic device′ differs from the electronic devicein that it also includes a transceiverthat communicates (e.g., two-way communication) with the processor. Signals, data and/or information received (e.g., wirelessly) by the transceiver(e.g., from a remote electronic device, such a smartphone, tablet computer, etc.) is communicated to the processor, and signals, data and/or information provided by the processor is communicated (e.g., wirelessly) by the transceiver(e.g., to a remote electronic device). Further, the function of the transceivercan be integrated into separate transmitter and receiver components.

200 The wireless electronic device′ can be used to communicate using a wide variety of communications technologies, including, but not limited to, 2G, 3G, 4G (including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (for instance, Wi-Fi), WPAN (for instance, Bluetooth and ZigBee), WMAN (for instance, WiMax), and/or GPS technologies.

260 260 2 FIG.B The transceivergenerates RF signals for transmission and processes incoming RF signals received from antennas. It will be understood that various functionalities associated with the transmission and receiving of RF signals can be achieved by one or more components that are collectively represented inas the transceiver. In one example, separate components (for instance, separate circuits or dies) can be provided for handling certain types of RF signals.

210 260 260 210 260 The processorprovides the transceiverwith digital representations of transmit signals, which the transceiverprocesses to generate RF signals for transmission. The processoralso processes digital representations of received signals provided by the transceiver.

3 3 FIGS.A-B 10 10 12 12 10 14 12 16 14 10 14 14 14 14 14 14 16 14 14 14 16 14 14 3 3 show a piezoelectric microelectromechanical systems (MEMS) microphone(hereinafter the “microphone”). The microphonehas a substrate. The substrateis optionally made of Silicon and may optionally have additional dielectric, metallic or semiconductor films deposited on it. The microphonecan have one or more piezoelectric sensors(hereinafter “sensors”) anchored to the substratein cantilever form with a gapbetween adjacent sensors. The microphoneconverts an acoustic signal to an electrical signal when a sound wave vibrates the sensors. The sensorscan be made from one or more layers of piezoelectric material. Optionally, the sensorscan be made at least in part of Aluminum Nitride (AIN). In another implementation, the sensorscan optionally be made at least in part of Scandium Aluminum Nitride (ScAlN). In other implementations, the sensorscan optionally be made at least in part of one of the following piezoelectric materials: Zinc Oxide (ZnO), Lead Zirconate Titanate (PZT), Polyvinylidene fluoride (PVDF, Lithium Niobate (LiNbO), Barium Titanate (BaTiO), Lead Magnesium Niobate-Lead Titanate (PMN-PT). The sensorscan include an electrode, which can optionally be made of aluminum (Al), molybdenum (Mo), titanium (Ti), titanium nitride (TiN), platinum (Pt), tantalum (Ta) or ruthenium (Ru), in some implementations. The gapsbetween the sensorsallow the sensorsto freely move, for airflow F to pass therethrough, and balance the pressure between both sides of the sensors. The gapcan be about 100-500 nm wide. The sensorsare preferably planar (e.g., flat), but are generally not completely flat due to a material internal stress gradient in the sensors.

4 4 FIGS.A-B 3 3 FIGS.A-B 3 3 FIGS.A-B 3 3 FIGS.A-B 4 4 FIGS.A-B 10 10 10 10 10 10 10 show a piezoelectric MEMS microphoneA (hereinafter “microphone”). The microphoneA is similar to the microphonein. Thus, references numerals used to designate the various components of the microphoneA are identical to those used for identifying the corresponding components of the microphonein, except that an “A” has been added to the numerical identifier. Therefore, the structure and description for the various features of the microphoneinare understood to also apply to the corresponding features of the microphoneA in, except as described below.

10 10 14 16 14 14 14 4 4 FIGS.A-B The microphoneA differs from the microphonein that the sensorsA are bent upward due to the material's residual stress or stress gradient thereof, resulting in an increased width of the gapsA between sensorsA. Thoughshow the sensorsA bent upward, in other examples, the sensorsA can bend downward due to material's residual stress or stress gradient thereof.

10 10 12 12 14 14 In use, the microphone,A is mounted on a printed circuit board (PCB) so that the substrate,A is disposed over or otherwise generally aligned with an opening in the PCB through which sound pressure enters the opening to deflect the sensors,A.

5 FIG. 10 14 16 14 10 14 16 14 16 10 10 10 10 shows a graph of sensitivity (in decibels or dB) versus frequency (in Hz). The solid line is representative of the performance of the microphone, where the sensorsare substantially planar (e.g. flat) and the gapis substantially constant between the sensorsalong their length. The dashed line is representative of the performance of the microphoneA, where the sensorsA are bent upward or downward and the width of the gapA varies between the sensorsalong their length, which results in an increased reduction in acoustic resistance (e.g., because the gapA is larger). As shown in the graph, the performance of the microphoneprovides better sensitivity in the low frequency range as compared to the performance of the microphoneA. That is, changes in frequency in the low frequency range result in a smaller dB change for the microphonethan for the microphoneA.

6 FIG. 14 12 14 15 12 15 14 15 14 15 14 15 15 shows a side view of one of the sensorsanchored on the substrate. The sensorhas one or more sensing electrodesA over a proximal portion thereof proximate to (e.g., adjacent) the substrate. A distal portionB of the sensorsdistal of the sensing electrodesA that extend to the free end of the sensorsdo not have electrodes thereon. In one implementation, the distal portionB of the sensorsonly has a mechanical function (e.g., receiving acoustic pressure thereon and deflecting or moving based on such pressure). In another implementation, the sensing electrodeA extends at least partially into the distal portionB.

6 FIG. 15 14 14 14 15 14 15 14 15 14 With continued reference to, the inventors have identified that increasing the rigidity of the distal portionB of the sensorscan advantageously increase the ability of the cantilevered sensorto resist deflection, for example, due to material internal stress gradient, without affecting the sensitivity of the sensor. However, the inventors realized that increasing the rigidity of the distal portionB of the sensorby increasing the mass of the distal portionB would negatively affect the operation of the sensoras it affect the resonant frequency, where mass on the distal portionB would reduce the frequency, thereby affecting the sensitivity of the sensor.

7 7 FIGS.A-C 7 FIG.B 140 120 140 10 140 120 16 140 140 show a piezoelectric sensor(hereafter “sensor”) anchored to a substrate. The sensorcan be incorporated into a piezoelectric MEMS microphone, such as the microphonedescribed above (e.g., the microphone can have multiple sensorscantilevered relative to the substrate, with gapsbetween the sensors). The sensorcan be cantilevered relative to the substrate as shown in.

140 142 120 145 142 146 140 140 142 145 140 142 145 140 140 140 140 140 140 The sensorhas a first portion(e.g., proximal portion) that is proximate to (e.g., adjacent to) the substrateand a second portion(e.g., distal portion) that extends from the first portionto a free end(e.g., unsupported end) of the sensor. The sensorcan have one or more electrodes (not shown) in the first portion(e.g., that in one implementation do not extend into the second portion). In some implementations, the sensorscan have one or more electrodes (not shown) in the first portionthat extend at least partially into the second portion. In some implementations, the sensorcan have multiple electrodes, for example, in the thickness direction of the sensor. For example, the sensor(e.g., a 1 μm thick piezo layer) can have an electrode on top (e.g., on a top surface of the sensor beam), an electrode on bottom (e.g., on a bottom surface of the sensor beam) and/or an electrode in between a top surface and a bottom surface of the beam of the sensor. In one implementation, the sensorcan be made of one layer of material. In another implementation, the sensorcan be made of multiple layers or films of materials, where the multiple layers have the same or different material stress gradients (e.g., due to the material property of the layer or film).

145 140 147 147 148 140 148 148 148 2 1 148 1 2 148 1 147 148 148 148 7 FIG.C The second portionof the sensorhas a corrugated section. In the illustrated implementation, the corrugated sectionhas multiple (e.g. two) grooves or recessesthat are spaced apart from each other by a pitch P (e.g., where the grooves alternate with ridges or larger thickness portions of the beam) and extend generally in the same direction (X direction) as the beam B of the sensor. The groovescan have a width W and depth D. In one implementation, the groovesextend substantially parallel to a central longitudinal axis CL of the beam B. With reference to, the groovescan have a height Hthat is greater than a height Hof side edges S of the beam B. In one implementation, the depth D of the groovesis approximately twice the height Hof the side edges S of the beam B. In one implementation, the depth D can be 1 μm. In one implementation, the height Hof the groovesis approximately double the height Hof the side edges S of the beam B. One of skill will recognize that the corrugated sectioncan vary, for example, in the number of grooves, angle of the groovesrelative to the center line CL of the beam B, length L, depth D, width W and/or pitch P of the groovesand fall within the scope of the invention. In some implementations, the length L can be between about 100 um and about 1 mm. In some implementations, the depth D can be between about 0.1 um and about 10 um. In some implementations, the width W can be between about 0.1 um and about 20 um. In some implementations, the pitch P can be between about 0.2 um and about 100 um.

147 148 16 140 147 140 140 147 145 140 147 140 147 Advantageously, the corrugated sectionwith the groove(s)extending generally in the same direction (X direction) as the length of the beam B increases the rigidity of the beam B in the longitudinal direction of the beam B and restricts deflection or bending of the beam B in the Z direction, for example in response to material internal stress gradient of the beam B. This results in a smaller gapbetween the sensorswhen subjected to the sound pressure. Additionally, because the corrugated sectionreduces or limits the bending of the distal portion of the beam B, this results in little to no effect on bending of the proximal portion of the sensor, and therefore it does not significantly affect the signal sensed by the electrodes of the sensor. Further, the corrugated sectionrestricts deflection of the beam B in the Z direction without adding to the mass or weight of the second portionof the sensor. The corrugated sectionallows the sensorto deflect or bend in the width (or Y) direction of the beam B. Advantageously, the corrugated sectioncan result in a reduction of deflection of at least 20% (e.g., 20-60%) reduction as compared to a sensor without the corrugated section.

7 FIG.D 7 7 FIGS.A-C 7 7 FIGS.A-C 7 7 FIGS.A-C 7 FIG.D 140 140 140 140 140 140 140 shows a schematic cross-sectional side view of a piezoelectric sensor′. Some of the features of the piezoelectric sensor′ are similar to features of the piezoelectric sensorin. Thus, reference numerals used to designate the various components of the piezoelectric sensor′ are identical to those used for identifying the corresponding components of the piezoelectric sensorin, except that an “′” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorinare understood to also apply to the corresponding features of the piezoelectric sensor′ in, except as described below.

140 140 148 148 148 The piezoelectric sensor′ differs from the piezoelectric sensorin that the walls of the grooves′ extend at an angle α (e.g., a non-perpendicular angle) relative to the base of the grooves′. In some implementations the angle α can be between 10 degrees and 90 degrees. In one implementation, the angle α can be between 60-70 degrees, such as about 60 degrees. Advantageously, the angle α of the grooves′ results in a more robust (e.g., stronger) corrugated section and inhibits defects therein.

7 FIG.E 7 FIG.D 7 FIG.D 7 FIG.D 7 FIG.E 140 140 140 140 140 140 140 shows a schematic cross-sectional side view of a piezoelectric sensor″. Some of the features of the piezoelectric sensor″ are similar to features of the piezoelectric sensor′ in. Thus, reference numerals used to designate the various components of the piezoelectric sensor″ are identical to those used for identifying the corresponding components of the piezoelectric sensor′ in, except that an “″”instead of an “′” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensor′ inare understood to also apply to the corresponding features of the piezoelectric sensor″ in, except as described below.

140 140 148 148 148 148 140 140 140 The piezoelectric sensor″ differs from the piezoelectric sensor′ in that the walls of the grooves″ are not only inclined (extend at an angle, e.g., a non-perpendicular angle, relative to the base of the grooves″), but the grooves″ are rounded. Advantageously, the rounded shape of the grooves″ of the corrugated section of the piezoelectric sensor″ can result in improved distribution of stress within the corrugated section (e.g., during operation of the sensor″) and improved reliability of the piezoelectric sensor″.

8 FIG. 8 FIG. 14 140 147 140 147 148 140 140 140 140 147 148 140 shows a comparison of deflection (in μm) between different piezoelectric sensor designs, namely a sensorwithout any corrugation, a sensorwith a corrugated section similar to the corrugated sectiondescribed above, and a sensor′ with a corrugated section′ that has grooves′ extending generally transverse (e.g., perpendicular) to a longitudinal axis of the sensor′. As shown in, the sensorwith the corrugated section having grooves extended in the direction of the length of the beam has the smallest deflection, relative to the sensorwithout any corrugation and relative to the sensor′ with the corrugated section′ with grooves′ extending generally transverse (e.g., perpendicular) to the longitudinal direction of the sensor′.

9 FIG. 8 FIG. 8 FIG. 8 FIG. 14 140 140 120 140 147 148 14 140 147 140 140 140 shows a graph of total displacement (in μm) along the length of the beam (in m) for the sensors,and′ shown in. In the graph, zero on the X-axis corresponds to the location where the beam B joins the substrate (e.g. substrate).shows that the sensorwith the corrugated sectionwith groovesextending in the same direction (X direction) as the length beam B exhibits a lower amount of deflection than the sensoror sensor′ (e.g., due to material internal stress gradient in the beam of the sensor). Additionally, as shown in, the increased rigidity provided by the corrugated sectionof the sensorto the second portion (distal portion) of the sensorresults in the second (distal) portion of the sensormaintaining a generally linear configuration.

10 FIG. 8 FIG. 10 FIG. 14 140 140 147 140 140 14 147 140 140 shows a comparison of output voltage from the sensor versus frequency for the sensors,,′ shown in.indicates that the inclusion of the corrugated sectionin the sensorhas minimal impact on output voltage provided by the sensor, as its output voltage increases by about 1% relative to the voltage performance of the sensorwithout any corrugation. Accordingly, incorporation of the corrugated sectionin the sensor, as described above, has minimal impact on the performance of the sensor.

11 11 FIGS.A-C 11 11 FIGS.A-C 7 7 FIGS.A-C 500 140 147 show cross-sectional views of structures illustrating steps of a methodof manufacturing a piezoelectric sensor, like the sensor, with a corrugated section, such as the corrugated sectiondescribed above.show cross-sections of the mold and beam in the widthwise direction (e.g., Y direction in).

11 FIG.A 502 shows the step of forming or providinga corrugated mold. The mold can be made of silicon, but other suitable materials can be used.

11 FIG.B 504 shows the step of forming or depositinga structure having one or more piezoelectric layers (e.g., one or more piezoelectric films) over the top surface of the mold to define the sensor beam with a proximal portion and a distal portion, the distal portion having a corrugated section including one or more grooves that correspond to the one or more grooves of the mold. For example, the one or more layers can be deposited onto the mold by one of many methods used for deposition of thin films, such as physical vapor deposition (PVD), Electron Beam Evaporation, Plasma Enhanced Chemical Vapor Deposition (PECVD), furnace deposition processes or a combination of these methods.

11 FIG.C 506 500 140 147 506 140 shows the step of releasing or removingthe structure with the corrugated section from the mold to form the cantilevered beam. Optionally, the methodof forming the piezoelectric sensorwith the cantilevered beam having the corrugated sectioncan be incorporated into a method for manufacturing a piezoelectric MEMS microphone. For example, the step of releasing or removingthe structure with the corrugated section from the mold can include leaving a portion of the sensor beam attached to a substrate in a cantilevered manner to provide the cantilevered sensorwith the corrugated section that can deflect, for example, when subjected to sound pressure.

12 13 FIGS.A andA 3 FIG.A 400 400 420 420 400 14 400 430 435 410 400 420 435 430 410 420 show triangular shaped sensors,A anchored to a substrate,A along one edge. The sensoris similar to the sensorinand has no corrugated section. The sensorA has a corrugated sectionA with multiple (e.g., three) groovesA that extend from the cantilevered or free endA of the sensorA toward the substrateA. The groovesof the corrugated sectionA extend at a non-parallel angle relative to each other (e.g., joining proximate the free endA and flaring out or diverging toward the substrateA).

12 13 FIGS.B andB 12 13 FIGS.A andA 12 13 FIGS.B andB 400 400 400 400 420 420 430 435 400 400 435 400 430 400 430 400 400 are graphs of total displacement (in μm) along the length of the beam for the sensors,A shown in, respectively. In the graphs, the right hand side on the X-axis corresponds to the juncture between the sensors,A and their respective substrate,A. As shown in, the corrugated sectionA with non-parallel groovesA of the sensorA exhibits a lower total displacement than the sensorthat does not have a corrugated section. Advantageously, even where the groovesA extend in a non-parallel direction relative to each other, the sensorA with the corrugated sectionA exhibits a lower amount of deflection than the sensorwithout a corrugated section (e.g., due to material internal stress gradient in the beam of the sensor). Additionally, the increased rigidity provided by the corrugated sectionA of the sensorA results in the second (distal) portion of the sensorA maintaining a generally linear configuration.

14 14 FIGS.A-E 140 400 400 show different examples of corrugated sections that can be incorporated into a beam of a piezoelectric sensor (such as the sensors,,A described above).

14 FIG.A 147 148 1 148 2 148 3 148 1 148 2 148 3 147 148 2 shows an example corrugated sectionA with groovesA,A,Athat are (linear and) angled relative to each other. In one example, the groovesA,A,Ataper toward each other at one end and move away from each other at an opposite end. The corrugated sectionA can be symmetrical about the center grooveA.

14 FIG.B 147 148 1 148 2 148 3 148 3 148 1 148 2 147 148 4 148 3 148 1 148 2 148 4 148 1 148 2 148 3 148 4 148 1 148 2 148 4 148 3 1 48 1 148 4 148 3 148 2 147 148 3 shows an example corrugated sectionB with three linear groovesB,B,Bthat are spaced apart from each other and extend parallel to each other, the grooveBdisposed between the other two groovesB,B. The corrugated sectionB also has a plurality of angled groovesBthat interconnect the center grooveBwith the outer groovesB,B. The angled groovesBcan extent at a non-parallel and non-perpendicular angle relative to the groovesB,B,B. For example, the angled groovesBcan extend at an acute angle relative to the outer groovesB,B. Angled groovesBbetween the center grooveBand outer grooveBcan extend generally at the same angle, and groovesBbetween the center grooveBand outer grooveBcan extend generally at the same angle. The corrugated sectionB can be symmetrical about the center grooveB.

14 FIG.C 147 148 1 148 2 148 3 148 3 148 1 148 2 147 148 4 148 3 148 1 148 2 148 5 148 3 148 1 148 2 148 4 148 4 148 5 148 4 148 5 148 1 148 2 148 3 148 4 148 1 148 2 148 5 148 1 148 2 147 148 3 shows an example corrugated sectionC with three linear groovesC,C,Cthat are spaced apart from each other and extend parallel to each other, the grooveCdisposed between the other two groovesC,C. The corrugated sectionC also has a plurality of first angled groovesCthat interconnect the center grooveCwith the outer groovesC,Cand extend in one direction and a plurality of second angled groovesCthat interconnect the center grooveCwith the outer groovesC,Cand extend in an opposite direction as the first angled groovesC. The first and second angled groovesC,Cdefine a generally V shape. The first and second angled groovesC,Ccan extend at a non-parallel and non-perpendicular angle relative to the groovesC,C,C. For example, the first angled groovesCcan extend generally at the same angle relative to the outer groovesC,Cand the second angled groovesCcan extend generally at the same angle relative to the outer groovesC,C. The corrugated sectionC can be symmetrical about the center grooveC.

14 FIG.D 147 148 1 148 2 147 148 3 148 1 148 2 148 3 148 1 148 2 148 3 148 1 148 3 148 1 148 2 shows an example corrugated sectionD with two linear groovesD,Dthat are spaced apart from each other and extend parallel to each other. The corrugated sectionD also has a plurality of angled groovesDthat interconnect the groovesD,D. The angled groovesDcan extend at a non-parallel and non-perpendicular angle relative to the groovesD,D. For example, the angled groovesDcan extend at an acute angle relative to the groovesD. The angled groovesDbetween the groovesD,Dcan extend generally at the same angle.

14 FIG.E 147 148 1 148 2 147 148 3 148 1 148 2 148 3 shows an example corrugated sectionE with two linear groovesE,Ethat are spaced apart from each other and extend parallel to each other. The corrugated sectionE also has a plurality of curved groovesEthat interconnect the groovesE,E. The curved groovesEcan optionally be defined by a constant radius (e.g., have a circular curvature).

140 410 147 430 140 410 140 410 140 410 The sensors,A described above included corrugated sections,A to strengthen the distal portion of the sensors,A and reduce bending of the sensor,A (e.g., of the distal portion of the sensors,A). In other implementations, discussed below, beams can be added to the sensors (e.g., via an additive process) to reduce bending, such as where sensor resonant frequency reduction due to additional mass is not a concern.

14 FIG.F 13 FIG.A 13 FIG.A 13 FIG.A 14 FIG.F 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorF. Some of the features of the piezoelectric sensorF are similar to features of the piezoelectric sensorA in. Thus, reference numerals used to designate the various components of the piezoelectric sensorF are identical to those used for identifying the corresponding components of the piezoelectric sensorA in, except that an “F” instead of an “A” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorA inare understood to also apply to the corresponding features of the piezoelectric sensorF in, except as described below.

400 400 147 148 400 148 1 2 148 1 2 148 2 148 148 148 148 148 7 7 FIGS.C-E The piezoelectric sensorF differs from the piezoelectric sensorA in that the corrugated sectionF includes multiple linear groovesF of different lengths that are formed in the sensorF, which has a triangular shape. Each of the groovesF extends from a proximal end Fto a distal end F. In the illustrated implementation, all of the groovesF have proximal ends Fthat are aligned with each other (e.g., end adjacent an imaginary straight line), and the distal end Fof each of the groovesF differs from the distal end Fof at least one other of the groovesF. The groovesF can in some implementations have a cross-sectional shape similar to that of the grooves,′ or″ in.

14 FIG.G 14 FIG.F 14 FIG.F 14 FIG.F 14 FIG.G 400 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorG. Some of the features of the piezoelectric sensorG are similar to features of the piezoelectric sensorF in. Thus, reference numerals used to designate the various components of the piezoelectric sensorG are identical to those used for identifying the corresponding components of the piezoelectric sensorF in, except that a “G” instead of an “F” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorF in, which is based on the description of the piezoelectric sensorA, are understood to also apply to the corresponding features of the piezoelectric sensorG in, except as described below.

400 400 147 148 1 148 148 148 1 1 148 400 1 148 1 148 1 148 1 148 14 FIG.G The piezoelectric sensorG differs from the piezoelectric sensorF in that the corrugated sectionG has multiple linear groovesG of different lengths, where the proximal ends Gof the groovesG are not aligned (e.g., do not end adjacent an imaginary straight line). As shown in, the groovesG closer to the centerline of the sensorG have proximal ends Gthat are located distally of the proximal ends Gof groovesG closer to the side edges of the piezoelectric sensorG. Such an arrangement (e.g., not aligned) of the proximal ends Gof the groovesG can advantageously inhibit the concentration of stress at the proximal ends Gof the groovesG. In one implementation, the proximal end Gof one grooveG can be offset from the proximal end Gof an adjacent grooveG by about 1 um to 2 um.

14 FIG.H 14 FIG.F 14 FIG.F 14 FIG.F 14 FIG.H 400 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorH. Some of the features of the piezoelectric sensorH are similar to features of the piezoelectric sensorF in. Thus, reference numerals used to designate the various components of the piezoelectric sensorH are identical to those used for identifying the corresponding components of the piezoelectric sensorF in, except that an “H” instead of an “F” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorF in, which is based on the description of the piezoelectric sensorA, are understood to also apply to the corresponding features of the piezoelectric sensorH in, except as described below.

400 400 148 2 148 1 2 148 1 148 2 148 2 400 The piezoelectric sensorH differs from the piezoelectric sensorF in that it includes edge groovesHthat confine the distal ends of the linear groovesH(e.g., the distal ends Hof the linear groovesHend at the edge groovesH). The edge groovesHcan optionally extend parallel to side edges of the piezoelectric sensorH.

14 FIG.I 14 FIG.G 14 FIG.G 14 FIG.G 14 FIG.I 400 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorI. Some of the features of the piezoelectric sensorI are similar to features of the piezoelectric sensorG in. Thus, reference numerals used to designate the various components of the piezoelectric sensorI are identical to those used for identifying the corresponding components of the piezoelectric sensorG in, except that an “I” instead of a “G” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorG in, which is based on the description of the piezoelectric sensorA, are understood to also apply to the corresponding features of the piezoelectric sensorI in, except as described below.

400 400 148 2 148 1 2 148 1 148 2 148 2 400 The piezoelectric sensorI differs from the piezoelectric sensorG in that it includes edge groovesIthat confine the distal ends of the linear groovesI(e.g., the distal ends Iof the linear groovesIend at the edge groovesI). The edge groovesIcan optionally extend parallel to side edges of the piezoelectric sensorI.

14 FIG.J 13 FIG.A 13 FIG.A 13 FIG.A 14 FIG.J 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorJ. Some of the features of the piezoelectric sensorJ are similar to features of the piezoelectric sensorA in. Thus, reference numerals used to designate the various components of the piezoelectric sensorJ are identical to those used for identifying the corresponding components of the piezoelectric sensorA in, except that a “J” instead of an “A” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorA inare understood to also apply to the corresponding features of the piezoelectric sensorJ in, except as described below.

400 400 147 148 1 148 2 148 3 400 148 1 148 2 148 3 400 2 148 1 148 2 148 3 148 1 148 2 148 3 400 1 148 1 148 2 148 3 The piezoelectric sensorJ differs from the piezoelectric sensorA in that the corrugated sectionJ includes multiple linear groovesJ,J,Jof different lengths that are formed in the sensorJ, which has a triangular shape. The groovesJ,J,Jextend at an angle relative to a centerline of the piezoelectric sensorJ so that distal ends Jof each pair of groovesJ,J,Jjoin each other (e.g., in the shape of a V). In one implementation, the groovesJ,J,Jextend substantially parallel to one of the side edges of the piezoelectric sensorJ. The proximal ends Jof the groovesJ,J,Jare aligned with each other (e.g., end adjacent an imaginary straight line).

14 FIG.K 14 FIG.J 14 FIG.J 14 FIG.J 14 FIG. 400 400 400 400 400 400 400 14 shows a schematic top view of a piezoelectric sensorK. Some of the features of the piezoelectric sensorK are similar to features of the piezoelectric sensorJ in. Thus, reference numerals used to designate the various components of the piezoelectric sensorK are identical to those used for identifying the corresponding components of the piezoelectric sensorJ in, except that a “K” instead of a “J” has been added to the numerical identifier. Therefore, the structure and description for the various features of the piezoelectric sensorJ in, which is based on the description of the piezoelectric sensorA, are understood to also apply to the corresponding features of the piezoelectric sensorK inKG, except as described below.

400 400 147 148 1 148 2 148 34 400 2 148 1 148 2 148 3 1 148 1 148 2 148 3 148 3 148 1 1 148 1 400 1 148 1 148 2 148 3 1 148 1 148 2 148 3 1 148 3 1 148 2 14 FIG.K The piezoelectric sensorK differs from the piezoelectric sensorJ in that the corrugated sectionK has multiple groovesK,K,Kof different lengths and that extend at an angle relative to a centerline of the piezoelectric sensorK so that distal ends Kof each pair of groovesK,K,Kjoin each other (e.g., in the shape of a V). The proximal ends Kof the groovesK,K,Kare not aligned (e.g., do not end adjacent an imaginary straight line). As shown in, the groovesKcloser to the centerline of the sensorK have proximal ends Kthat are located distally of the proximal ends Kof groovesKcloser to the side edges of the piezoelectric sensorK. Such an arrangement (e.g., not aligned) of the proximal ends Kof the groovesK,K,Kcan advantageously inhibit the concentration of stress at the proximal ends Kof the groovesK,K,K. In one implementation, the proximal end Kof one grooveKcan be offset from the proximal end Kof an adjacent grooveKby about 1 um to 2 um.

15 FIG.A 640 642 645 648 645 648 648 648 640 648 645 640 640 645 shows a top view of a piezoelectric sensor(hereafter “sensor”) with a proximal portionand a distal portion. One or more beamscan extend over the at least a portion of the distal portion. In one implementation, the beam(s)can extend linearly. In one implementation, the beam(s)can be spaced apart from each other (e.g., at constant intervals) and extend parallel to each other. In one implementation, the beam(s)can extend parallel to a central axis of the sensor. The beam(s)can strengthen the distal portionof the sensorto reduce bending of the sensor(e.g., bending of the distal portion), such as due to sound pressure.

648 648 648 The beam(s)can in one implementation have a length of between 50 μm and 500 μm. In one implementation, the beam(s)can have a width of between 0.1 μm and 10 μm. In one implementation, the beam(s)can have a height of between 0.1 μm and 1 μm.

648 648 148 648 In one implementation, the beam(s)can include a dielectric material, such as one or more of Silicon oxide, Silicon nitride, and silicon-oxynitrides; other suitable dielectric materials are possible. In one implementation, the beam(s)can include a metal, such as aluminum (Al), copper (Cu), platinum (Pt), ruthenium (Ru), and Titanium (Ti); other suitable metals are possible. In one implementation, the beam(s)can include a metal nitride, such as Tantalum Nitride (TaN), Titatinum Nitride (TiN), Aluminum Nitride (AlN), and Scandinum Aluminum Nitride (ScAlN); other suitable metal nitrides are possible. In one implementation the beam(s)can include amorphous silicon.

15 FIG.B 640 640 640 650 650 640 650 648 640 645 640 648 640 648 shows a cross-section of the sensorduring a step in a manufacturing process (e.g., additive process) of the sensor. The sensorcan be formed on a substrate. The substrateis optionally made of Silicon and may optionally have additional dielectric, metallic or semiconductor films deposited on it. The sensor beamcan be defined by one or more piezoelectric layers (e.g., one or more piezoelectric films) formed or deposited over the top surface of the substrate. The one or more beam(s)can be formed or deposited over a top surface of the sensor beam(e.g., over the distal portionof the sensor beam) by depositing (e.g., sputtering) the material of the beam(s)over the sensor beamstructure, and patterning of the material to form the beam(s).

15 FIG.C 640 648 650 612 650 640 648 612 640 640 shows the step of releasing or removing the sensor beamwith the beam(s)on its top surface from the substrate, leaving a portionof the substrateon either side of the cantilever sensor beam(with the beams) that can deflect, for example, when subjected to sound pressure. The portionand sensor beamforms a structure with a cavity through which sound pressure travels to the sensor beam.

While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the systems and methods described herein may be made without departing from the spirit of the disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure. Accordingly, the scope of the present inventions is defined only by reference to the appended claims.

Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

Of course, the foregoing description is that of certain features, aspects and advantages of the present invention, to which various changes and modifications can be made without departing from the spirit and scope of the present invention. Moreover, the devices described herein need not feature all of the objects, advantages, features and aspects discussed above. Thus, for example, those of skill in the art will recognize that the invention can be embodied or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. In addition, while a number of variations of the invention have been shown and described in detail, other modifications and methods of use, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is contemplated that various combinations or subcombinations of these specific features and aspects of embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the discussed devices.